Osteoarthritis and articular cartilage injuries are very common, typically causing pain, swelling and reduced mobility leading to functional impairment. The treatment cost for patients suffering from these conditions are massive with an estimated annual economic cost of $65 billion in the US alone. Magnetic resonance imaging facilitates non-invasive imaging of articular cartilage in vivo. However, manual analysis is tedious, inaccurate, and irreproducible and no computer- aided tool is commercially available to analyze high-resolution 3-D MR cartilage image data. This proposal is for development of quantitative analysis of articular cartilage morphology and tissue composition in highly congruent joints (knee, ankle) from anatomical and multi-contrast 3-D magnetic resonance images. The main innovation of the proposed approach is that the multiple surfaces of adjoining bones and cartilages in the entire joint will be segmented simultaneously in 3-D rather than independently border-by-border and slice-by-slice in 2-D, thus taking advantage of 3-D contextual information with an expected improvement in 3-D segmentation performance. Multi-contrast MR tissue characterization will identify 6 cartilage tissue types in a volumetric fashion. The specific aims of this Phase-I proposal are to: 1) Develop a method for comprehensive morphometric analysis of articular cartilage over the complete joint surface from volumetric high-resolution MR images. 2) Develop a method for cartilage tissue characterization from volumetric multi-contrast MR images. 3) Develop a prototype Cartilage Analyzer software suite and assess its performance in human cadaver and in vivo ankles and knees. The overarching goal of the Phase II research is to build and validate a prototype system for quantitative cartilage analysis that will be utilized by orthopedic clinicians treating osteoarthritis, orthopedic surgeons, musculoskeletal radiologists, and researchers for epidemiologic and pharmacologic studies, as well as by MR scanner manufacturers. Following cardiovascular diseases, cartilage diseases are the second most frequent cause of illness. When measured in days of illness, cartilage diseases actually exceed the impact of cardiovascular diseases. The treatment cost for patients suffering from these conditions are massive with an estimated economic cost in the USA of $65 billion annually. As a result, articular cartilage research is a highly topical field with very significant practical implications and applications for future patient management and care. [unreadable] [unreadable] [unreadable]